Recently, biotechnology has brought development of new research and industrial fields through technical cooperation and fusion with various science fields. Particularly, BIT (Bio-Information technology) has been developed by using technologies that has been researched in the field of semiconductor technology, and BINT (Bio-Information Nanotechnology) has been developed as a new technological field by fusion with Micro/Nano technology. The fusion biotechnology has been actively researched because it can greatly contribute in analyzing functions and interaction of biomaterials in the fields of disease diagnosis, new medicine development and signaling system analysis that has been importantly researched in the biotechnological fields at present. Particularly, a bio-sensor has been actively researched as a bio-diagnosis technology.
The bio-sensor is a hybrid device of a semiconductor chip type that is formed by integrating and mixing substances such as DNA (deoxyribonucleicacid), protein, enzyme, antibody, microorganism, animal or plant cell and organ and neuron cell in a solid substrate formed of inorganic material such as a semiconductor in high density. The bio-sensor is used to obtain biological information such as expression of gene, gene combination and protein distribution, or to increase biochemical process and reaction speeds or information processing speed. The bio-sensor is roughly classified into a bio-optical detection method and a bio-mechanical detection method.
The bio-optical detection method is a method of detecting reaction of phosphorylated biomaterial using a fluorescent microscope, and includes an ELISA (enzyme-linked immunosorbent assays), FRET (fluorescence resonance energy transfer) and a method using electrophoresis typically. The bio-mechanical detection method is a method of directly detecting change of surface energy generated during chemical reaction of biomaterial as mechanical displacement. The bio-mechanical detection method does not require process of attaching phosphorous material during detection procedure (label-free), and have high detection resolution, and can be reused. Thus, recently, the fusion biotechnologies have been researched actively.
By using a lap-on-a-chip, it is possible to perform various processes such as separation, purification, mixing, reaction and detection of a sample on a single chip by using the MEMS technology. The lap-on-a-chip technology is a method that can continuously analyze various samples of very small amount, perform high-speed analysis and miniaturize a size of the entire device. Thus, the lap-on-a-chip is suitable for a portable device.
A conventional bio-diagnosis technology requires high-scale and expensive instruments because the bio-diagnosis technology uses a bio-optical analysis method mainly. However, the lap-on-a-chip provides a technology that can miniaturize the instruments by using the MEMS technology. The lap-on-a-chip has many advantages, but has problems such as development of methods for precise fluid flow control and highly sensitive detection for commercialization.
Particularly, in the field of a bio-sensor, fluid flow channel formation technology, pump, valve have been actively researched with development of the MEMS technology. However, there is a difficult problem that a laser and a spectrophotometer should be miniaturized to manufacture the conventional bio-sensors based on the optical analysis method in the type of the lap-on-a-chip.
A bio-mechanical detection analysis using a fine cantilever arrangement requires pre-treatment processes such as thin gold film deposition and surface treatment for immobilization of biomaterial. In addition, the bio-mechanical detection analysis requires a laser-displacement measuring system for measuring displacement of nanometer scale generated by reaction of the biomaterial. In addition, the bio-mechanical detection analysis method has a disadvantage in that it is very sensitive to temperature because of bimetal effect caused by differences of thicknesses and thermal expansion coefficients of the cantilever structure (silicon nitride film) and thin gold film.
Accordingly, development of a bio-sensor for a high performance lap-on-a-chip by using a bio-compatible material and a new detection method has been strongly demanded.